Nerve-muscle Transmission Flashcards
NT of NMT and NMT is?
Ach
Active zones on motor end plate of post synaptic muscle cell is?
Junctional folds
What fits into junctional folds
Presynaptic nerve terminal
In NMT, there is convergence of inputs
T/F
F. Just one presynaptic nerve terminal to one motor end plate
What is a motor end plate of post synaptic muscle cell
thickened portion of the post synaptic muscle cell membrane at the NMJ
Size of synaptic cleft in NMJ
30nm
Contents of synaptic cleft in NMJ
ISF which is rich in Ca,Na,glucose, and Achesterase
What covers post synaptic muscle cells
Sarcolemma
Post synaptic muscle cell receptors are called
Muscle cell nicotinic AChRs
Effects of influx of Ca into vesicle in NMT
It activate actin-myosin interaction
Effect of Na influx in post synaptic muscle cell
Generation of a protomotive force called end plate potential
What causes AP in NMT
EPP creates a current sink that depolarizes the membrane till AP is fired
NMT can be bi-directional
T/F
F. It’s always unidirectional
Delay period of NMT is how long?
0.5msec
NMT is easily fatigued
T/F
T. Due to repeated stimulation and depletion of Ach and ATP
How can we block NMT?
Curare. Competitive Ach antagonist
Effect of calcium and magnesium on NMT
Ca supports
Mg inhibits
Which is more
Ach molecules or Ach receptors
Ach molecules
By like 10 times
EPP is always subthreshold to AP
T/F
F. It’s always Suprathreshold
EPP is faster to generate than mEPP
T/F
F. They have the same time course(1msec)
What hydrolyses ACH
Ach esterase
choline is actively taken up while acetyl is passively taken up into axoplasm of presynaptic nerve terminal
T/F
T
What are the substrates for Ach formation
Choline and acetyl coA
What’s the enzyme for Ach formation
Choline acetyl transferase
What moves Ach into vesicles
vesicular acetylcholine transporter
List the 4 phases of excitability of muscle cells and the threshold needed to re-stimulate them
ARP- nothing
RRP- Suprathreshold
Supra normal-subthreshold
Subnormal- Suprathreshold
Condition of skeletal muscle in myasthenia gravis
Weak and easily fatigued
Describe myasthenia chemically
due to the body producing antibodies that bind to the AchR; this AchR-antibody complex is now destroyed by phagocytes
What is a paraneoplastic disorder
Disorders in which the effects of cancer occur at a site remote from the primary tumor
MG is common more in which sex
Females
Myotonia dystrophy is hereditary and recessive
T/F
F.it’s heriditary and dominant
Skips some generations tho
Cause of myotonia dystrophy
Abnormal Na or Cl channels caused by mutated 7,17,19 muscle protein
Characteristics of myotonia dystrophy
Contraction with no relaxation
Muscle wasting and weakness
Cattarh, atrophied gonads made worse by cold fatigue and emotion
Difference between duchenne’s dystrophy, limb girdle dystrophy and Becker’s dystrophy
DD:absent dystrophin
BD:altered or reduced dystrophin
LGD: altered or reduced dystrophin
Treatment of altered dystrophin issues into utrophin
Take a drug that coverts utrophin into dystrophin
McArdle’s Syndrome.
Discuss
exercise intolerance. You work out and it leads to build up of harmful metabolites and breakdown of muscle
What covers a sacromere
sarcolemma
What covers sacrolemma
basal lamina
sarcoplasmic reticulum ends in?
terminal cisternae
T system of tubules invaginates from—- and contacts the ——- between the —— band and —-band —— in every sacromere
Sacromere Myofibrils A band I band Twice
What makes up a triad in a sacromere
One T tubule and 2 adjacent terminal cisterns
Difference between A band I band H band M line Z line
Z lines are in the I bands(light)(actin
- M lines are in A bands(dark)(myosin)
- H band is a lighter shade in A bands
To contact skeletal muscle, Ca is released from which part of the sacromere
Sarcoplasmic reticulum
Ca from sarcoplasmic reticulum binds to ——— to ———-
Troponin C
To uncover the myosin binding site on actin
How many heads does myosin have
2
From one Z line to another Z line makes a -
Sacromere
What binds troponin I and T together
Troponin C
Sliding of actin and myosin is what bond
Hydrogen bonding
What covers the heavy head of myosin
Troponin T
Heavy head of myosin is also called ?
Active site of myosin
What covers active site of actin
Troponin I and tropomyosin
Difference between isometric and isotonic contraction
Metric: constant length ;postural muscles
Tonic: varying length; axial muscles
Difference between type 1 and 2 of skeletal muscle fibers in terms of Names Glycolytic ability Oxidative ability Prolonged exercise Extremities Myoglobin content Capillary density Ca pumping capacity Myosin ATP rate Energy source
Xterics Type 1 Type 2 Names Slow Fast Names Red White Names Oxidative Glycolytic Myoglobin content High Low Capillary density High Low Ca pumping capacity Moderate High Myosin ATP rate Slow Fast Energy Phosphorylcreatine & ATP Glycolysis Prolonged exercise Yes! No
T tubules use - receptors
Sarcoplasmic reticulum uses— receptors
Dihydropiridine
Ryanodine
Differentiate between skeletal, cardiac , and smooth muscles under the following. Fatigue Sacromere Summation Tetanus
S(possible);C(not);Sm(not)
S(present);C(present);Sm(not)
S(possible);C(not);Sm(possible)
S(possible);C(not);Sm(possible)
MG is common in which gender more?
Female
